Lawn mower sharpener



July 4, 1950 A. slLFEN LAWN MOWER SHARPENER Filed Dec. 1l. 1946 PatentedJuly 4, 1950 LAWN SHARPENER Alfred Silfen, Berkeley, Ill., assignor toNorman H. Gerlach, Chicago, Ill.

Application December 11, 1946, Serial No. 715,583

(Cl. '7B-82.1)

1 Claim.

This invention relates to law mower sharpeners of the type shown anddescribed in my U. S. Patent No. 2,327,827, granted August 24, 1943; andmy primary object is to modify and improve the Sharpener of theabove-identified patent, as well as other similar Sharpeners, in f suchmanner that it may be applied to lawn mower brush bars of various widthsand made slidably to lit the brush bar, irrespective of the widththereof, so that the mower blade guide will remain at a iiXed distancefrom the brush Other objects of the invention and the vari- I ousadvantages and characteristics of the present lawn mower Sharpener willbe apparent from a consideration of the following detailed description.

A preferred embodiment of my invention is illustrated in theaccompanying drawing, where- Fig. 1 is a vertical sectional view of aconventional lawn mower, to which is shown applied a Sharpener inaccordance with the invention;

Fig. 2 is a perspective viewof my improved Sharpener;

Fig. 3 is a bottom view of the Sharpener; and

Fig. 4 is a fragmentary perspective view emphasizing a detail which isnot shown with Suflicient clarity in the other figures of the drawing.

Referring to Fig. 1, the conventional lawn mower therein shown comprisesthe usual laterally spaced wheels I which rest on the lawn surface IIand are journaled in a pair of laterally spaced frame members I2. Arotor I3 mounted on and driven by a shaft I4 spans the space betweenframe members I2 and carries at its periphery four equally spaced cutterblades I5 having the usual helical formation lengthwise of the rotor. Acutter bar I6 is bridged between the two frame members I2 and aiiixedthereto and has a cutting edge Ia disposed in co-operative relation tothe cutting edges of blades I5. Shaft I4 is connected through suitablegearing to one or both wheels I0 and rotates in the same direction asthe wheels.

The two frame members I2 are tied together in spaced relation by cutterbar I6 and a brush bar I1. The latter extends parallel to shaft III andis connected at its ends to the respective frame members.

Vupon the top surface of brush bar Il.

The lawn mower is provided with the usual handle I8 which is pivotallyconnected to the frames by means of a yoke I9.

A freewheelingdevice,` not shown, permits rotor I3 to rotate in aclockwise direction, as viewed in Fig. 1, independently of wheels I0.

The improved Sharpener includes a two-piece bar 20 comprising metalstrips 2| and 22 which are bent to form, conjointly, an inverted U-shaped guide or bridge portion 23 which, as shown in Fig. 1, is adaptedto overlie and straddle the brush bar Il. y

A rod 24 of circular cross-section is loosely journaled at its two endsin aligned holes 25 and 26 in the two vertical portions 2Ia and 22a ofthe inverted U-shaped guide and is headed over at its ends to secure apair of washers 21 which serve to hold said rod in place. Rod 24functions as a roller bearing and is designed to rest It facilitatesmovement of the Sharpener lengthwise of the brush bar in the course ofthe blade-sharpening operation and serves permanently to connect thestrips 2| and 22.

A short at le 28 is secured to the under side of strip 2l by means of aclamp 29 comprising a horizontal top portion 30 and two parallelvertical spaced wall portions 3| and 32 which terminate at their lowerends in angularly extending ears 33 and 34. The latter embrace oppositeedges of le 28 and serve to support the same in clamping engagement withthe under surface of Strip 2|. The two vertical wall portions 3l and 32are provided with rectangular openings to accommodate strip 2I; and thetop portion 3B is tapped to receive a thumb screw i135, the lower end ofwhich is adapted to bear against the top surface of strip 2| whereby to-apply an upwardly directed force to clamp 29.

lUpon loosening thumb screw 35, clamp 29, together with le 28, can bemoved lengthwise of strip 2I, and by so doing the le can be positionedso as to produce the desired bevel or clearance angle on the cutterblades I5. This adjustment is necessary in order to adapt the `Sharpenerfor use on lawn mowers which differ from one another as respects thelocation of the brush bar relatively to the rotor.

The ends of ears 33 and 34 are so spaced as to enable le 28 to bebrought into contact with a cutter blade, but they are situated so closeto the respectively adjacent sides of the blade that they function asguides to keep the blade properly oriented in relation to the le as thesharpener is moved lengthwise of the blade; and since each blade isdisposed helically with respect to the axis of rotation of the rotor,said ears cause the rotor to rotate to such extent as to keep thatportion of the blade which is being operated upon at any instant inproper angular relation to the file. Thus, the clearance angle or bevelon each cutter blade is kept uniform from end to end.

The brush 'bar IH 'is not-of any 'fixed or standard width, as viewed inFig. '1, but varies considerably as between diierent makes and models oflawnmowers. But it is desirable that the Sharpener be maintained in axed position laterallyzofv-the brush bar because any substantialmovement thereof crosswise of the rotor l3=-will alter the' angularityof the bevel on the cutter blade `=being sharpened, and, for thatreason, ymay result in a defective sharpening job.

For the purpose of adapting the Sharpener to brush bars of variouswidths, I have provided an adjustable connectionfbetweenzmetal strips2f| and 2-.1which fena'bles the `spacing between vertical portions Ziaand 22a to be 'altered in conformity :with the width of the'particularAbrush-bar to which Tftheidevice .is Lto 'be connected, thus. making itpossible to obtain a yclose running ron thel brush bar, irrespectiveoffits width, r

' lThe adjustable Y'Conner-,tion is effected fby *over -l-a'ppfingnthecontiguousfend portions '2lb and 22h .of the `two metal strips 2id.andZZ and'byf'providing fthe fend .portion 22h with 1an elongate slotv:36 through which extends a vertical clamping bolt The latter extendsthrough ya 4holewin the central 'pertionr of the @end -portion 2lb- .andis equipped 4with a wing nut 38,' 'together `with `a wa'sher. As shownin the 7drawingthe `fclarnp bolt Yis :arranged so that the wing vnut'isat'the top and its head is :at the bottom. The'head vof the bolt 'restskon'the rod 2l! and hence the latter 4 that there are numerous possiblemodications and alternative embodiments within the scope and purview ofmy herein described invention,

and I, accordingly, do not wish to be limited except as indicated by theterms of the appended claim. Having described my invention, what I claimas new and desire to secure by Letters Patent is:

As asnew article of manufacture, a Sharpener adapted for useinsharpenin'g theblades of a conventional lawn mower with a bladeequipped rotor `and a brush bar above and forwards of the rotor, randfcomprising an elongated two-piece frame consisting of a rst at metalstrip adapted when the *Sharpener `is in use to extend substantially'horizontally 'and having its outer end shaped t0 nform a handle yand,its inner end bent upwards serves to hold the bolt 'against :axialdisplacement with-respect to'f'the 1.end portions, J2lb :and 22h. Bolt:3l 'and wing glut '38 fare i'effective to clamp togetherthe twooverlapped end portions 2 l'b 4and 221). As shown most clearly in Figfl,vthe end portion '2lb is provided with an upstanding ear Zic whichslidably fits slot 236 and thus .'Serves, inAcohj-unction'with bolt '31,-to hold the two strips I2i fand "22 iin alignment.

'Roller 2li is long enough to 'permit .the vertical portions Ela and222e to beseparated sufciently toem'brace the-widest brush bar likely to.be'encountered, Aand. enough longer so that the 'washers 2i' will notinterfere with free rotation lof the roller when said vertical yportionsare spaced :apart to the maxi-mum extent.

With `the Sharpener vadjusted freely toiit the brushfbar laterally,andthe Vclamp .29 positioned so as to produce `an appropriate clearance'angle or'bevel, the operator has only to .apply the fsharpener to themower in the manner depicted in Fig. l `and 'then -move it back andvforth 'along the brush lbar. yIn so fdoing he may conveniently grip thetwo slightlyupturned ends of bar 20. I-Iedoes notneed to observe anyprecaution against movements Vof the Sharpener `laterally of the rotorbecause that is prevented by virtue ofthe lfact thatthe Sharpener-'hasbeen adjusted closely to t the brush bar laterally.

f It willbe `apparent to persons skilled in the lart at right angles andthen outwards at right angles to form a substantially ,vertical sideportion and a substantially horizontal top portion, and a secyondulat'Ametal ystrip arranged `in :longitudinal alignment lwith ftheiirs't'str-ip, having the outer iend-'there'o sh'apedto form alhandle and itsinner bent-upwards atl-right angles and thenfoutwards iaft-'rightanglesto form a substantially vertical/side portion and a substantiallyhorizontal topportion, and arranged so that the top 'portion 'thereof:is in vlapped relation ywith the top portion c'f the iirst strip andlalso'so -that its side and top portions vdeiine Awith :the side and topportions of said rst strip an inverted U-shaped brush bar receivingguide, -aconne'ction yoperative toconnect `Ithe two Astrips so that'they4may :be Aslidably ad- 'usted "toward one `efnotlfier in order to varythe width of said guide vand 'consisting of a `longitudinally extendingclosed ended slot inone of the top portions and a'vertieally extendingnut equipped bolt extending through the 'slot and a hole 'in the topportion of theother strip, and'arranged so that the "head thereof lis atthe bottom and the nut is at the top, a roller type brush bar VengagingArod disposed 'beneath and lengthwise of said top portions, positionedso that it underlies the head of the bolt and holds the bolt in place,

v extending loosely throug'h holes in the upper ends ofsaid sideportions,v embodying abutment forming heads at its ends, and serving 'tohold the two strips in permanently connected relation while at the sametime permitting the strips to be slidably adjusted to and from oneanother, and means on, and adjustable longitudinally of, theintermediate 1portion of vone of said strips for retaining .a 'bladesharpening iile against lthe bottom Yface of said intermediate portionand also guiding the blade at 'the top of the rotor with respect .tothefile .during use `of the Sharpener.

` REFERENCES CITED The following :references are 'of record in the ilevof this patent:

' UNITED' STATES PATENTS Number `Name Date 617,584 VJ,.Leshure Jan. l0,1899 1,359,192 Palas NOV. 16, 1920 11,489,492 Gardner Apr. 8, 1924'2,327,827 .Silfen ..Aug.. 24, A194:3

